Lobsters, Crabs Feel Pain, Don't Just Respond To Stimulus: Research

It would seem an excruciating end for millions of crustaceans, plucked from the sea, bound, impaled, torn apart limb by limb and finally boiled alive.

We freely do things to shellfish that we would never be allowed to do to any living thing that has a spine because of the commonly held notion that they can't feel a thing.

Now, that belief is being challenged.

In an address this week to Behaviour 2013 the world's biggest gathering of animal behaviour scientists, a researcher presented strong evidence that crustaceans do, in fact, greatly mind their odyssey to the dinner plate.

The idea is that when crabs are offered two dark shelters -- but only one that will electrocute them -- they will learn to choose the non-shocking home.

If crabs relied only on nocireceptors -- basically an involuntary twitch that fires off in the face of potentially damaging stimuli -- they would not actually learn to avoid the shocking shelter.

Researchers concluded that such behaviour is "consistent with key criteria for pain experience and are broadly similar to those from vertebrate studies."

Another experiment saw hermit crabs making motivational trade-offs to avoid pain -- passing on, for example, their preferred abode when they were laced with minor shocks. Instead, they readily accepted the offer of a new home.

“Assessing pain is difficult, even within humans,” Elwood told the Newcastle conference, adding there is a “clear, long-term motivational change [in these experiments] that is entirely consistent with the idea of pain”.

The findings run contrary to earlier research suggesting lobsters and the like don't feel a thing. Rather, they twitch and squirm based purely on reflex.

In a 2005 study, Norwegian scientists concluded that simple nervous systems and tiny brains prevent everything from lobsters down to the humble earthworm from feeling the hurt.

Indeed, Wenche Farstad, who chaired the panel that reported to the government, said fisherman need not shy away from driving a hook into a live worm.

"It seems to be only reflex curling when put on the hook. They might sense something but it is not painful and does not compromise their well-being," he told the Guardian at the time. "The common earthworm has a very simple nervous system. It can be cut in two and continue with its business."

But animal rights activists were quick to comment on Elwood's experiments, suggesting that invertebrates should be afforded the same basic protections that their back-boned cousins receive.

While the issue of whether mice feel pain remains inconclusive, under the law, they are given the benefit of the doubt, Robert Hubrecht of the Universities Federation for Animal Welfare told Nature.

“We’re behaving in an illogical way at the moment,” he said, adding, "This is somewhere science has to lead.”

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